Drainage Contractor November 2017 : Page 38

U.K. UPDATE A conversation about soil by Rob Burtonshaw I can’t think of many things more underappreciated than soil. The earth below our feet is vital for life: the vast majority of our food depends upon it and without it humanity would end. Yet how many people make that association? For example, the vitality of oxygen and water is embedded in our minds as essential to life. Soil by comparison is overlooked and often denigrated. This is true of the general public, but also farmers, and I’m convinced that part of our job as drainage contractors is to remind anyone who cares to listen of the importance of soil and the level of water in that soil. As soil health becomes more important, drainage needs to be part of that conversation. It doesn’t matter what sector of agriculture you operate in, the basics of farming are the same: increase yields, protect crops, and protect and encourage soils. Managing water levels in the soil falls into the last of these principles and I suspect that all contractors see the effect drainage has. Waterlogged soils can’t produce strong healthy crops. Excess water fills all the gaps and cavities in the soil forcing out oxygen and creating anaerobic conditions. Crops cannot thrive and yield is low. The solution is pipe in the ground, a man-made exit of the excess water. Soils are a natural ecosystem: dynamic, complicated and varied. There are many different ways to achieve good drainage, and when picking the right method, one of the primary considerations is the soil type. I often think that here in the U.K. we get the raw end of the deal. I know I’m wrong, but the grass is often greener on the other side of the fence and the temptation to whinge is sometimes too strong to restrain. Our soils, here in sunny Warwickshire, roughly in the middle of green and pleasant England, are heavy, sticky clays. Our offices are on the site of a former Brickworks and if I wanted to make some traditional red bricks, the raw material is pretty close. Add to this the British weather, which I suspect all will know, has a tendency to vary from drizzle to rain – the water that falls tends to take its time to soak into the soil. More often than not a British contractor is trying to remove water from the surface or close to the surface on top of clay soils, this means a stone backfill on top of the drains and often some form of secondary drainage, such as mole ploughing or subsoiling. Compare this to the Netherlands where most soil types are extremely light. In England, we have another word for the type of soil so fruitfully farmed by the Dutch – sand. There is no need for a stone fill, the soil itself can do the job and the water permeates the soil quickly and easily. Normally Dutch contractors are controlling the water table and trying to prevent ground water from rising too high in the soil profile. However, before I start to daydream about emigrating to the Netherlands freeing myself from my clay quagmire, light soils have different problems. The large particle sizes found in sandy soils move more freely and then often fall gently to the bottom of pipework in drains with a shallow gradient. Dutch drains need jet washing each year and even with such maintenance they do not last long. Sometimes deeper sacrificial drains are required, to allow the junction to be installed in the dry, pumped outlets are common. Contractors in the Netherlands and in the U.K. area trying to achieve the same goal, using the same tool, but using that tool in different ways because of the nature of the soil. The soil and its characteristics are the boss, we have to follow its lead. I will embrace it, celebrate it and promote it. I guess its starts here. DC 38 DRAINAGE CONTRACTOR | NOVEMBER 2017